Novel Multiple-frequency Q-switched Fiber Laser by using chirped fiber Bragg grating Fabry-Perot etalon

We propose a novel approach to increase the repetition rate of all-fiber Q-switched laser. This proposed ring cavity fiber laser consists of a fiber Bragg grating (FBG) functions as the wavelength discriminator and a chirped FBG Fabry-Perot (FP) etalon serve as the transmission filter inside the ring cavity. The Q-switching operation is achieved by periodically tuning of the FP etalon and hence modulating the loss of the cavity. A numerical model is developed to simulate this type fiber ring laser with consideration of FBGs' spectra. Our simulation shows that the repetition rate of the Q-switched pulse can be increased by multiple times that depend on the tuning range and the bandwidth of the chirped FBG FP etalon. Experimentally we achieved 14 kHz Q-switched pulses under 3.5 kHz PZT modulation frequency.